CST334 - Week 7

Write what you learned this seventh week in CST 334

Topic: Persistence

This week, we covered a critical area of operating systems—persistence. The readings focused on how the operating system interacts with I/O devices, particularly highlighting DMA (Direct Memory Access) and PIO (Programmed I/O). DMA allows data transfers between devices and main memory without the CPU's direct involvement, freeing it up for other tasks. In contrast, PIO requires the CPU to handle each data transfer, which consumes CPU time and limits its ability to perform other operations simultaneously

We also discussed the role of hard disk drives and RAIDs in maintaining data persistence. Persistence refers to the ability of a storage system to retain data even when the system is powered down. Hard disk drives achieve persistence by storing data magnetically on platters, ensuring that the data remains accessible even if power is lost unexpectedly. RAIDs offer additional persistence through redundancy, protecting data from failures by storing duplicate copies across multiple disks. For example, in RAID 1, data from the first drive is mirrored, or duplicated, to the other drive. This setup ensures that if the primary drive fails, all your data is still backed up on the second drive.